This is a straight rod occurring singly and in pairs. It is usually motile by peritrichous flagella. Gram reaction is negative. Gas is produced from sugars, and most strains produce hydrogen sulfide. It is a very common cause of opportunistic infections found in feces of man and animals without any symptoms of disease, and in water, sewage, soil, and food. Diseases caused include nosocomial infections of the respiratory, urinary, and circulatory systems, and localized infections when the microbe gains access to otherwise healthy tissues. Growth is at 35-37 C.